Flying With a Dog or Cat in the Cabin: Carrier Sizes, Fees and Tips

Most US airlines let a small dog or cat travel in the cabin with you, inside a carrier that fits under the seat in front. It is usually the calmest way for a small pet to fly. The catch is that every airline sets its own size limit, fee and number of pets per flight, and those change. Use this page to prepare, then confirm the details on your airline's pet policy page before you book.

The rules almost every airline shares

• The carrier goes under the seat in front of you and your pet stays inside it for the whole flight.
• One pet per passenger is the norm. Some airlines allow two small pets of the same species in one carrier.
• Limited spots. Airlines cap the number of pets per flight, so add your pet when you book, not at the airport.
• Minimum age. Most US airlines require pets to be at least 8 weeks old for domestic flights. International trips often require older pets.
• Paperwork. A recent health certificate from your vet is commonly requested, and proof of rabies vaccination is often needed for international travel. Destination countries can have their own rules.
• The fee is per flight. Chewy's airline guide puts typical in-cabin fees at roughly $35 to $150 each way.

Carrier size limits by airline

These are the figures listed in Chewy's airline pet policy guide, last updated in October 2025. Treat them as a starting point and check the airline before you fly, because policies change.

Notice the height: often around 9 inches. That is why soft carriers are so popular. A soft carrier can squash slightly to fit under the seat, while a hard one cannot.

Choosing a carrier

Your pet should be able to stand up and turn around inside. Measure your pet standing, from nose to base of tail and from floor to the top of the head, then compare with the carrier's inside dimensions, not just the outside. Mesh panels for airflow, a zip that cannot be nosed open, and a shoulder strap all make the airport easier.

If you fly often, a premium carrier with a firmer structure and better materials is worth the higher price.

A hard plastic kennel is too bulky for most cabins, but it is the safer choice for car trips and vet visits.

How to prepare your pet

1. Start weeks ahead. Leave the carrier open at home with a blanket and treats inside, so it becomes a den.
2. Practice short trips. Zip them in for a few minutes, then a car ride, then longer.
3. Book the vet visit for the health certificate in good time, and ask about travel anxiety if your pet gets stressed.
4. Keep the meal light before the flight to reduce the chance of an upset stomach, but offer water.
5. Walk your dog right before going through security, and look for the airport's pet relief area.
6. Pack a small kit: a puppy pad in the carrier, a spare pad, wipes, a few treats and a collapsible bowl or travel bottle.

At security

In the US, your pet does not go through the X-ray machine. You take them out of the carrier and carry them, or walk them on a leash, through the metal detector while the empty carrier is screened. A harness on a cat makes this much safer than holding them loose.

Bigger dogs

Dogs too big for an under seat carrier fly as checked baggage or cargo, where airlines allow it, and that comes with breed, temperature and crate rules. If that is your situation, talk to your vet and read the airline's cargo policy carefully. For more carrier options, see our guide to carriers and playpens.

Questions people ask

Sources

• Chewy: The Complete Airline Pet Policy Guide for U.S. Airlines (updated Oct 2025)